I haven't seen many suggestions of bags for the Q1 so I thought I would try. Except for the slipcase that comes with the Q1 and the portfolio available from Samsung, no one else seems to make a dedicated Q1 case. I've seen a few reports of people using daytimers or CD cases and removing the rings. I've got o few case suggestions of my own.
I use a Targas 14" slip case for every day use because I can carry around a few files as well. For a smaller case, I've got a pouch that's like a very small messenger case. Its a Royal Taveller by Samsonite brand that I picked up at office Depot but cant find a link anywhere. The Samsonite has lots of room for the PowerBank spare battery.
I've also found that most DVD cases will work fine, they just tend to be a little bulky. Also the Case Logic Nylon Pad folio is a nice fit, even it it's a bit big for the Q1. Obviously most tablet PC cases may also work and many large portfolio style cases will work as well. Until there are more
Q1 specific cases, you have lots of options you just have to be creative.